The use of mineral trioxide aggregate in one-visit apexiï¬cation

The use of mineral trioxide aggregate in one-visitapexification treatment: a prospective study

S. Simon1,2, F. Rilliard2, A. Berdal1 & P. Machtou2

1Laboratory of Oro-facial Biology and Pathology, INSERM U714, University of Paris 6, Paris; and 2Department of Endodontics

and Restorative Dentistry, School of Dentistry Garanciere, University of Paris 7, Paris, France

Abstract

Simon S, Rilliard F, Berdal A, Machtou P. The use of

mineral trioxide aggregate in one-visit apexification treatment:

a prospective study. International Endodontic Journal, 40, 186–

197, 2007.

Aim To assess the outcome of apexification using

mineral trioxide aggregate (MTA).

Methodology Fifty-seven teeth with open apices on

50 patients referred for root canal treatment received

an apexification procedure in one appointment with

MTA by the same operator. Patients were recalled at

6 months, 12 months and every year thereafter. Blind

to the treatment record, two examiners assessed the

pre-treatment, post-treatment and control radiographs

of the study patients in a dark room using a magnifier.

Each apex visible on the radiographs was scored with

the periapical index (PAI), and the size of the apical

lesion was measured. The presence of an apical bridge

was also noted. Kappa-Cohen test was used for exam-

iners calibration. The paired t-test was used for

statistical analysis of apical healing.

Results Forty-three cases were included with at least

12 months follow-up. When considering the PAI score

and the decrease in size of the apical lesion, healing

occurred in 81% of cases.

Conclusion Apexification in one step using an

apical plug of MTA can be considered a predictable

treatment, and may be an alternative to the use of

calcium hydroxide.

Keywords: apexification, immature tooth, mineral

trioxide aggregate, prospective clinical study.

Received 6 June 2006; accepted 14 September 2006

Introduction

The completion of root development and closure of the

apex occurs up to 3 years following eruption of the

tooth (Nolla 1960). After crown formation, the inner

and outer enamel epithelium develop as a two-layered

epithelial wall to form Hertwig’s epithelial root sheath

(HERS), which plays a key role in the differentiation of

odontoblasts. When the first layer of dentine has been

laid down, HERS begins to disintegrate and only the cell

rests of Malassez persist in the periodontal ligament. At

the same time, HERS progresses in an apical direction

until complete formation of the root.

When teeth with incomplete root formation suffer

pulp necrosis, the root development ceases and apical

closure cannot be achieved. Root canal treatment at

this time is a significant challenge, because of the size of

the canal, the thin and fragile dentine walls and the

large open apex. Apexification is defined as ‘a method

to induce a calcified barrier in a root with an open apex

or the continued apical development of an incomplete

root in teeth with necrotic pulp’ (American Association

of Endodontists 2003). The goal of this treatment was

to obtain an apical barrier to prevent the passage of

toxins and bacteria into the periapical tissues from the

root canal. Technically, this barrier is also necessary to

allow the compaction of the root filling material.

Calcium hydroxide pastes have been considered as

the material of choice to induce the formation of a hard

tissue apical barrier. Its efficiency has been demonstra-

ted by many authors, even in the presence of an apical

lesion (Chosack et al. 1997, Felippe et al. 2006). This

Correspondence: Stephane Simon, Laboratory of Oro-facial

Biology and Pathology, INSERM U714, University of Paris 6,

15-21 rue de l’Ecole de Medecine, 75006 Paris, France

(e-mail: [email protected]).

International Endodontic Journal, 40, 186–197, 2007 ª 2007 International Endodontic Journal

doi:10.1111/j.1365-2591.2007.01214.x

186

chemical has several disadvantages, such as variability

of treatment time (average 12.9 months) (Dominguez

Reyes et al. 2005), difficulty of the patient’s recall

management, delay in the treatment and increase in

the risk of tooth fracture after dressing with calcium

hydroxide for extended periods (Andreasen et al. 2002,

Felippe et al. 2005, Andreasen et al. 2006).

Alternatives to calcium hydroxide have been pro-

posed; the most promising being mineral trioxide aggre-

gate (MTA�) (Shabahang et al. 1999, Shabahang &

Torabinejad 2000, Witherspoon & Ham 2001, Steinig

et al. 2003). The advantages of this material are

multiple: (i) reduction in treatment time, (ii) possibility

to restore the tooth with a minimal delay, and thus to

prevent the fracture of the root and (iii) it also avoids

changes in the mechanical properties of dentine because

of the prolonged use of calcium hydroxide.

In addition, because of its noncytotoxicity (Osorio

et al. 1998), MTA has good biological properties

(Torabinejad et al. 1995, Torabinejad et al. 1998) and

stimulates repair (Economides et al. 2003). When used

in dogs’ teeth with incomplete root formation and

contaminated canals, MTA induced the formation of an

apical barrier with hard tissue (Shabahang et al. 1999).

In a prospective study on 26 immature teeth

apexification treatment with calcium hydroxide

showed a high prevalence of apical healing and apical

closure (Felippe et al. 2006) with the formation of a

hard tissue barrier. To date, no clinical study has been

published to evaluate the outcome of a one-visit

apexification treatment with MTA.

The aim of this prospective study was to verify the

effectiveness of apexification using MTA in one appoint-

ment, by reviewing 50 patients who had received this

treatment.

Material and methods

The study period was from June 2001 to June 2005. All

the patients referred for root canal treatment on a tooth

with an open apex were included in the study, after

obtaining informed consent. Alternative treatment

options were discussed with the patients and their

referring dentists. Main exclusion criteria were general

medical contraindications (one case of heart disease

and one case of severe immunodeficiency) or a contra-

indication for endodontic treatment (fracture of the

tooth, tooth unrestorable).

Fifty-seven teeth were treated on 50 patients (20

female and 30 male). Forty-three patients (26 male, 17

female) received one treatment and seven patients

(three female and four male) had two teeth treated.

Distribution of the treated teeth is shown in Table 1.

Root canal treatment

All treatments were performed using the same protocol

by the same operator (Figs 1–5):

1. A preoperative radiograph was taken with a film-

holder using a paralleling technique.

2. Infiltration for local anaesthesia with articaine and

1/100 000 adrenaline (Ubistesin – 3MESPE, Cergy

Pontoise, France).

3. Restoration of the tooth if needed and isolation of

the tooth with rubber dam.

4. Access cavity with round diamond bur (diameter

014), Endo Z� bur (Dentsply-France Ballaigues, Switzer-

land) and Sonic inserts (Sonic Flex, Kavo, Roissy, France).

5. Canal debridement with Hedstrom file.

6. Copious irrigation with sodium hypochlorite (5%).

7. Determination of the working length on radiograph

with the carrier (Messing Gun� – Produits Dentaires,

Vevey, Switzerland) placed in the canal.

8. Drying of the canal with a sterile blunt paper point

(Size X Coarse, Henry Schein, Paris, France).

9. Placement of the MTA (White Pro-Root MTA�,

Dentsply Maillefer, Ballaigues, Switzerland) apical plug.

The cases number 1–11 were treated with Grey MTA

and the cases number 11–57 with White MTA, the

marketing of the grey one having been suspended.

Table 1 Distribution and follow-up of the treated teeth

Tooth Total

Preoperative

radiograph

Preoperative + 1

follow-up

Preoperative + 2

follow-up

Preoperative + 3

follow-up

11, 21 43 38 31 11 3

12, 22 1 1 1 1 0

14, 15, 24, 25 1 1 1 1 0

16, 17, 26, 27 9 8 8 1 0

31, 41 1 1 1 1 0

36, 46 2 1 1 0 0

Total 57 50 43 15 3

Simon et al. Apexification and MTA

ª 2007 International Endodontic Journal International Endodontic Journal, 40, 186–197, 2007 187

10. Radiological examination of the apical plug, and

adjustment if needed with an endodontic plugger.

11. Completion of the filling of the apical third with

MTA, to 5 mm from the radiographic apex.

12. Temporary filling with a moist cotton pellet and

Cavit� (ESPE, Cergy Pontoise, France).

13. Postoperative instructions and nonsteroidal anal-

gesics were prescribed if necessary.

14. Filling of the whole canal was completed by Schil-

der’s warm vertical compaction of gutta-percha and Pulp

canal sealer (Kerr Manufacturing Co., Romulus, MI,

USA), and corono-radicular restoration was completed

with a bonded resin composite in the following 7 days.

Evaluation

Patients were recalled for clinical and radiographic

examinations every 6 months for 2 years, and every

year thereafter. Periapical radiographs were taken

using a paralleling technique with a film holder. At

the end of the study, the last review occurred at

6 months for 14 teeth (25%), at 12 months for 21

teeth (37%), at 18 months for six teeth (10.5%),

24 months for 10 teeth (17%) and 36 months for six

teeth (10.5%). Blind to the treatment record, two

examiners assessed the pre-treatment, post-treatment

and review radiographs of the study patients in a

Figure 1 Tooth treated by renewing

calcium hydroxide in the canal. After

1 year of treatment no signs of healing

were evident, and the patient com-

plained of recurrent swelling.

Apexification and MTA Simon et al.

International Endodontic Journal, 40, 186–197, 2007 ª 2007 International Endodontic Journal188

darkened room using a magnifier (2.5·). Periapical

status of each root was categorized with the periapical

index (PAI) (Ørstavik et al. 1986). When an apical

lesion was present, its largest dimension was recorded.

The presence or absence of a visible apical closure was

also recorded.

Randomization

The operator (SS) randomized the entire sample using

odd numbers. Two examiners (P.M., F.R.) assessed the

PAI scoring, lesion diameter and the presence of apical

closure for all teeth in the sample, blinded to unaware

of the stage of the treatment.

Statistical analysis

Data were recorded on Excel 2002� (Microsoft Inc.,

Redmond, WA, USA). The Kappa-Cohen test was used

for examiner calibration, following the recommenda-

tions described by Landis & Koch (1977). The paired

t-test was used for analysis of quantitative data, i.e. PAI

scoring and apical lesion diameter, between preopera-

tive and postoperative radiographic examinations. The

Figure 2 After canal disinfection, the

MTA carrier is placed in the canal to

determine the working length on the

radiograph.



chi-squared test of Pearson was used for distribution

comparison. The Kappa test was performed with

Microsoft Excel draft product of Department of Psychol-

ogy, Universite de Quebec a Montreal (http://www.er.

uqam.ca/nobel/r30574/). Statistical analysis was com-

pleted with Sigma Stat. 2.03, (spss Inc., Chicago, IL,

USA).

Results

The mean age of the patients was 18 years (SD ¼ 12),

16 years (SD ¼ 10) for male patients and 20 years

(SD ¼ 14) for female patients (Table 2). There was no

statistically significant difference in distribution by

gender, or age between the genders.

Fifty-seven teeth were examined preoperatively and

43 teeth for 12 months or more postoperatively

(exhaustivity ¼ 86%).

Examiner calibration

The result of the first calibration, on 10 radiographs,

was j ¼ 0.87 (Po ¼ 0.95, Fc ¼ 0.65). Then 108

randomized radiographs were analysed by the two

examiners, and the apical status of 394 roots was

recorded by each examiner. When the periapical status

Figure 3 An apical plug of MTA depos-

ited in the apical 2 mm of the root canal

and condensed with sterile paper cones

(X Coarse Size).



was not recordable because of radiographic impreci-

sion, the score not interpretable (NI) was attributed.

After the first analysis, the Kappa-Cohen test value

was j ¼ 0.69 (n ¼ 394, Po ¼ 0.79, Fc ¼ 0.32); with-

out the score NI, j ¼ 0.74 (n ¼ 316, Po ¼ 0.85,

Fc ¼ 0.41). j being inferior to 0.81, a second obser-

vation of cases with divergent results (n ¼ 34) was

undertaken by each examiner. Examiner 1 changed his

score for 13 cases, and Examiner 2 changed his score

for 21 cases. After this rereading, there was no

significant difference between the two examiners (v2,

1ddl, ¼0.95, P < 0.40), suggesting that there was no

influence of one examiner to the other. With this

analysis, the Kappa test value was j ¼ 0.83

(Po ¼ 0.88, Fc ¼ 0.31) with the NI score and

j ¼ 0.94 (Po ¼ 0.96, Fc ¼ 0.39) without the NI

score. The new Kappa-Cohen score was superior to

0.81 and the results could be used for the statistical

analysis. It was decided to eliminate the NI score.

PAI score

The comparison of the PAI scores between the preop-

erative radiograph and the last review radiograph,

analysed with the paired t-test, showed a statistically

significant reduction in the pathology on the whole of

Figure 4 The length of the apical plug

of MTA must be at least 5 mm.



the sample (t ¼ 4.83, 42ddl, P < 0.001). On the first

control, the PAI increased for six teeth (14%) and

remained stable for 10 teeth (26%). No improvement in

the PAI was noted in seven cases (16%), and the score

decreased for 27 teeth (63%). On the first review, the

rate of failure to heal was thus 30% (13 teeth: seven

with increasing score of PAI and 6 teeth which did not

present any sign of healing).

In this study, ‘absolute rate’ was defined as the

increase (absolute failure rate) or decrease (absolute

success rate) in the PAI score; ‘relative rate’ corres-

ponded to the absolute rate added to the cases with

stability of the PAI but different of 1 (relative failure

rate) or cases with stability of PAI ¼ 1 (relative success

rate).

On final review, the PAI increased in six cases (14%),

was stable (but >1) in 6 cases (14%), decreased in 29

cases (67%) and remained equal to 1 in two cases. So,

the absolute failure rate was 14%, the relative failure

rate was 28%; the absolute success rate was 67% and

the relative success rate was 72%.

Size of the apical lesion

A comparison of the size of apical lesion (¼0 by defect)

at baseline and following review showed a statistically

Figure 5 Root canal filling completed

during a second visit by warm compac-

tion of gutta-percha.



Tab

le2

Su

mm

ary

of

the

clin

ica

lca

ses

an

dre

sult

s*

Case

nu

mb

er

Male

/

fem

ale

Ag

e

(years

)

To

oth

nu

mb

er

JO

6m

on

ths

12

mo

nth

s18

mo

nth

s24

mo

nth

s36

mo

nth

s

Last

reca

ll

(mo

nth

s)

Fin

al

PA

I

-in

itia

l

PA

I

Siz

eo

f

lesi

on

(Fin

al

dia

mete

r-in

itia

l

dia

mete

r)(m

m)

Ap

ical

barr

ier

PA

I

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)Fo

rmati

on

Tim

e

(mo

nth

s)

1M

16

11

31

22

40

)1

)1

·18

2M

14

11

22

136

)1

0

3M

18

21

22

21

00

4M

17

11

513

47

13

)1

)5.5

5F

26

21

54

212

)3

)4

6a

11

54.5

45

13

)1

0.5

7M

911

45

112

)3

)5

·12

8F

53

27

32

315

0)

2

9M

10

11

33

21

36

)2

)3

·18

10

F51

11

44.5

212

)2

)4.5

11

M34

15

46.5

32

19

)2

)6.5

12

F42

11

21

22

)1

0

13

M10

11

44.5

32

224

)2

)2.5

14

M34

31

59

32

24

)3

)9

15

F9

11

11

14

00

·12

16

F8

11

21

11

22

)1

0·

12

17

M7

11

44

31

022

)3

)4

18

M10

21

44

32.5

218

)2

0·

18

19

M12

11

32.5

44

11

35

)2

)2.5

·24

20

M8

11

45

11

14

)3

)4

21

F30

17

45.5

45

43

24

0)

2.5

22

27

47

45

18

0)

2

23

M42

16

53.5

312

)2

)3.5

24

bF

836

45

515

13

110

25

F12

11

511

33.5

24

)2

)7.5

26

M9

11

54

118

)4

)4

·18

27

M37

16

42.5

42

12

0)

0.5

28

M10

16

11

12

00

29

M22

11

46

44

12

0)

2

30

F17

11

12

17

10

31

F26

11

45

32.5

12

)1

)2.5

32

21

58

32.5

12

)2

)5.5

33

M35

16

13

15

20

34

26

13

12

20



significant reduction on the whole of the sample

(t ¼ 4.34, 42ddl, P < 0.001).

In 28 cases (65%), the observers measured an

increase in the width of the ligament ‡ 1 mm on the

preoperative radiographs; the diameter decreased in 26

samples and increased in two samples between the

initial radiograph and the last review. There was no

case of development of a lesion after treatment.

With reference to the size of the lesion, the absolute

success rate (completely healed lesions) was 65%, the

relative success rate (healed lesions and lesions in

process of healing) was 95%; and the absolute failure

rate (lesions enlarging) was 5%.

Size of the lesion and PAI

By considering that the addition of absolute success of

the two criteria were required to consider the treatment

as successful, the apexification treatment with MTA

was successful in 77% of the cases (33 teeth); the

relative success rate (including the healing in process

was 81%. Absolute failure rate was 16% (seven cases)

and relative failure rate was 19% (eight cases)

(Table 3).

Apical foramen closure

An apical barrier was distinguishable in 11 cases

(26%). In nine cases, this barrier appeared in a context

of absolute success. In one case, the bridge was visible

in a context of relative success, the PAI being stable

and no lesion being present. In the last case (case 38),

an apical barrier was present, despite the PAI score

increasing from 1 to 2. This case was considered as an

absolute failure. Considering that the appearance of a

dentinal bridge is a sign of success, the success rate

should be 88% (38 cases out of 43).

In case 6, the PAI score decreased (5 to 4) but the

size of the lesion increased (4.5–5 mm). The last review

was at 12 months postoperativly and because of the

recurrent clinical symptoms and the complaint of the

patient, apical surgery was undertaken.

Discussion

Apexification has been investigated in many studies

(Goldman 1974, Morse et al. 1990, Rafter 2005), and

especially the clinical use of calcium hydroxide (Farhad

& Mohammadi 2005). A recent prospective clinical

study showed a success rate of 100% for this technique,

the mean time necessary for the formation of an apicalTab

le2

Co

nti

nu

ed

Case

nu

mb

er

Male

/

fem

ale

Ag

e

(years

)

To

oth

nu

mb

er

JO

6m

on

ths

12

mo

nth

s18

mo

nth

s24

mo

nth

s36

mo

nth

s

Last

reca

ll

(mo

nth

s)

Fin

al

PA

I

-in

itia

l

PA

I

Siz

eo

f

lesi

on

(Fin

al

dia

mete

r-in

itia

l

dia

mete

r)(m

m)

Ap

ical

barr

ier

PA

I

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)P

AI

Siz

eo

f

lesi

on

(mm

)Fo

rmati

on

Tim

e

(mo

nth

s)

35

M8

11

11

33

2.5

36

20

36

M7

21

31

11

36

)2

0·

12

37

M14

11

45

212

)2

)5

38

M10

12

12

224

10

·24

39

M7

11

44

22

22

)2

)4

40

F19

11

21

12

)1

0

41

F15

21

54.5

44

13

)1

)0.5

42

M12

21

31

12

)2

0·

12

43

M8

11

58.5

212

)8.5

*T

he

case

sw

ith

less

than

12

mo

nth

sfo

llo

w-u

p(1

4te

eth

)d

on

ot

ap

pear

inth

ista

ble

beca

use

they

have

no

tb

een

reta

ined

for

the

stu

dy.

aA

nap

ical

surg

ery

was

un

dert

eke

nat

12

mo

nth

s(r

ecu

rren

tsw

ell

ing

).bT

he

too

thw

as

extr

act

ed

at

12

mo

nth

s.



barrier being 12.19 months (Dominguez Reyes et al.

2005). In such a treatment, the formation of the apical

barrier is necessary to allow the filling of the root canal

system without risk of over filling. Failure of this

technique may be because of several factors: (i) a

repeated overfilling with the material with a high pH

(12.7) can induce a necrotic zone in the periapical

bone; (ii) the lack of coronoradicular restoration and

thus of an appropriate coronal seal whilst the canal

system is not filled; (iii) a prolonged contact with

calcium hydroxide induces a significant decrease in

intrinsic properties of the exposed dentine. These last

two factors are directly responsible for many root

fractures occurring before the end of the treatment

(Rafter 2005).

To avoid this risk of fracture, several authors

(Witherspoon & Ham 2001, Linsuwanont 2003,

Andreasen et al. 2006) proposed a technique of apex-

ification in one visit, by placing an apical plug of MTA

in the last 5 mm of the canal. Obturation of the root

canal system and placement of a coronal restoration in

the tooth immediately are thus possible, and are

regarded as key elements for the long-term conserva-

tion of the treated tooth (Goldberg et al. 2002, Steinig

et al. 2003).

Several case reports have been published. Biological

apical closure appears later, i.e. after the filling of the

root canal, contrary to the technique with calcium

hydroxide, where obtaining the apical barrier is neces-

sary to complete the root canal treatment. Recently, in

an experiment on dogs, Felippe et al. (2006) concluded

that MTA induced in all the treated teeth the formation

of an apical barrier. It would appear that no clinical

study on outcome of apexification with MTA has been

published. Nevertheless, treatment outcome is an

important part of evidence based practice. It is the

basis of treatment planning and prognostic considera-

tions (Peak et al. 2001). The aim of this work was to

determine whether the treatment of apexification with

MTA in one stage has constant and predictable results

after a sufficient period of follow-up.

The results of the present study indicate a success

rate of 81%; thus, it can be considered as predictable.

Nevertheless, further studies including more patients

and a longer period of survey should be undertaken to

confirm these results. In this work, all the treatments

were carried out by the same operator, a specialist in

endodontics. The validation of this procedure for

general practitioners is necessary.

The PAI score was used to evaluate the periapical

health and the healing process because it was

considered as the most appropriate of all the evalu-

ation techniques validated in endodontics. However,

PAI scoring is not ideal for the evaluation of

immature teeth; histologically the periapical area

during the root formation is different from the mature

tooth due to cell differentiation, the presence of HERS

and bone reorganization. The sensitivity of interpret-

ation of radiographs on immature teeth seems to be

insufficient to allow precise scoring of 1 or 2 for

example. Nevertheless, the results presented here

regarded a score 1 as health apically. Limits of the

PAI score in such a study should affect the results, by

decreasing the success rate.

Contrary to the study of Dominguez Reyes et al.

(2005), a healing response occurred in 81% of cases.

Dominguez Reyes et al. (2005) considered only incisors

in young patients whereas the present study included

all teeth with a large canal and open apex, in young

patients and adults. This difference in patient and case

selection could explain the difference in the results.

The study ended at a defined date, and took into

consideration those cases that were followed up for at

least 12 months, as recommended by Ørstavik (1996).

That is why 57 teeth were initially included in the

study, but 43 were retained for the prospective analy-

sis. In one case, the PAI was stable but greater than 1,

and the size of apical lesion decreased at 1 year. This

case was considered as a relative failure; a review in

few months will be necessary to confirm continuing

healing. Thus, the success rate was affected by the limit

of the observation time.

Table 3 Correlation between Periapical index (PAI) score and size of the lesion

PAI

decreasing

(absolute success)

PAI

stable ¼ 1

(relative success)

PAI stable > 1

(relative success)

PAI increasing

(absolute failure)

Size of lesion decreasing (absolute success) 21 0 5 0

Size of lesion ¼ 0 (relative success) 7 2 1 5

Size of lesion stable > 0 (relative failure) 0 0 0 0

Size of lesion increasing (absolute failure) 1 0 0 1



Biological process of apical closure

Histologically, induction of apical hard barrier tissue

formation has been described and validated by Felippe

(Felippe et al. 2006) in 100% of the animals treated. In

the present study, apical closure was noted only in 26%

of cases. This difference could be because of the

interpretation of the radiograph and the limited thick-

ness of the dentine bridge that was too thin to be clearly

distinguishable.

Biological process

Investigations have been done on the HERS (Zeichner-

David et al. 2003) and cell differentiation during root

and apical odontogenesis, but none about the real

biological process of apical barrier formation. To date,

no explanation about the process of apical formation

after pulp necrosis nor about the process of activity of

MTA is available. The material is proposed for several

applications (pulp capping, apical surgery and perfor-

ation treatment). In all these situations, cell differen-

tiation seems to appear. Felippe et al. (2006) showed

that the bridge seems to be formed by bone and not

dentine.

In the pulp capping procedure with MTA, the dentine

bridge obtained is thicker, and its direct contact with

the dentine walls ensures a better sealing than that

obtained with calcium hydroxide. For apexification, no

histological investigations have been done to compare

the quality of the apical barrier obtained with MTA and

calcium hydroxide.

A better comprehension of the biological process and

especially about the role of MTA is necessary to

understand the healing process and eventually to

develop new clinical procedures.

Conclusion

These results show that apexification in one visit by

placing an apical plug of MTA is a predictable and

reproducible clinical procedure. More investigations are

necessary about the biological process of apexification,

and the activity of MTA in contact with cells, especially

its potential role in cell differentiation and wound

healing.

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The use of mineral trioxide aggregate in one-visit apexiï¬cation